Watch double-decker demolition of Seattle's viaduct

Crews have started demolition on the double-decker portion of Seattle's Alaskan Way Viaduct.

Author:
Allison Sundell

Published:
4:54 PM PDT March 11, 2019

Updated:
5:49 PM PDT March 19, 2019

SEATTLE — Crews have started demolishing the double-decker portion of the Alaskan Way Viaduct on Seattle's waterfront.

The Washington State Department of Transportation said that 22 million tons of concrete and steel from the viaduct have already been removed. In the first three weeks of demolition, crews took down roughly 1,460 feet of the structure near the Columbia ramp, Pike street, and viaduct's north end.

Rubble cleared from the site is broken into small pieces and used to fill the Battery Street Tunnel.

Photos show that the off-ramp to Western Avenue has been rubblized as well.

A worker hoses down the construction site as the Western Avenue off-ramp from the Alaskan Way Viaduct in Seattle is demolished on March 3, 2019.

WSDOT

Work on the segment of the viaduct that’s directly north and south of Columbia Street is expected to last through the end of March. That includes time to set up fences around the site, prepare it for construction, and restore the ground after demolition is complete.

That portion of the viaduct will be the first double-decker section of the roadway to be removed. So far crews have worked south from the Battery Street tunnel on lanes that are positioned side-by-side and on a small section of the southbound lanes directly in front of Pike Place Market.

When crews demolish the double-decker section, they will remove concrete pieces from the top deck first letting the rubble fall onto the bottom deck. They will then remove stringers, girders, and floorbeams followed by upper columns that extend to the lower level. Finally, contractors will remove the lower deck in the same manner.

(Diagram: WSDOT)

Demolition work has been underway for about 3 ½ weeks after record-breaking snow forced crews to delay the start date by several days.

The entire demolition process is expected to take about six months, but WSDOT expects the main section of the viaduct to be completely demolished by June.